1. Field of the Invention
The present invention relates to liquid, pasty, thixotropic materials, which can be molded and hardened, for adhesive, gluing, putty, sealer and coating purposes. These materials are based on the reaction products of monomeric, oligomeric and/or polymeric carboxylic acids or derivatives of carboxylic acids, especially esters, which can be hardened and which have an acid number greater than 0.1, with compounds of metals of the second group of the periodic system, especially oxides and hydroxides, which are capable of forming salts. The invention furthermore relates to a process for the manufacture and hardening of such materials. For the sake of simplicity, the materials are referred to herein as "adhesive and coating materials".
2. Description of the Prior Art
According to the present state of the art, the rheological properties of adhesive and coating materials, based on carboxylic acids and their derivatives, such as, unsaturated polyester resins, can be altered only with mineral fillers and/or thixotroping materials, such as, colloidal silica, and others, such as, bentonites, in order to attain stable, pasty materials. Through the use of such thixotroping and/or filler materials in resin mixtures for adhesive and coating materials, the rheological properties can be modified in such a manner that the materials obtained can be processed in the specific field of application. However, the use of such thixotropic and modifier materials results in certain disadvantages.
One of these disadvantages, when only inert fillers are used for the manufacture of sediment-free, stable materials, is that the final properties are changed very greatly if the fillers are used in excessive amounts. When only known, thixotroping materials are used, stable materials are obtained which are, however, frequently too soft, greasy and have a "gel-like" character. Some of these disadvantages can be eliminated by the combined use of known thixotroping materials and inert fillers. However, the materials so modified are also sticky at the surface or they sweat or leach out liquid components, as a result of which they are not readily moldable and cannot be handled.
Materials filled with inert fillers, especially materials based on unsaturated polyesters, have the further disadvantage that they have a limited shelf-life, since they slowly harden or show a typical "drying effect" during storage. Therefore such materials frequently have a shelf-life of only a few months, as a result of which their use in many areas becomes impossible. Also, the frequent, relatively high shrinkage and the crack formation of such materials are also negative phenomena.
A further disadvantage, when working such fillers and/or thixotroping materials into resins and resin mixtures, arises from the fact that the viscosities increase very rapidly and that therefore the required amount of filler, for achieving a maximum "packing effect" can frequently not be worked in.
In the case of the addition of a large amount of known thixotroping materials and fillers, the hardening conditions are changed to such an extent, that they can only be compensated for by an above-average addition of reaction initiators. The major consequence however of such an overcatalysation is the fact that short-chain polymers are formed, which have completely different and inferior properties than comparable, unfilled materials.
In addition, the known thixotroping materials are frequently more expensive than the resins and resin mixtures themselves so that, in the case of large additions for achieving thixotropic adjustments, the products become considerably more expensive. It is a further disadvantage that, for achieving filled, thixotropic resin mixtures, mixing aggregates with high pumping efficiencies are required.
A further problem resides in the fact that such products can presently be supplied only as two-component or multi-component products, in the use of which, errors can arise during mixing the individual components. Those, not skilled in the art, cannot evaluate and judge the importance of such errors in mixing. Therefore, in many areas, noncritical materials are requested, which require no further manipulation, such as, weighing, mixing or homogenizing before use.
In order to avoid some of the above disadvantages, an attempt was made in preceding years to attain single-component systems by the use of incorporation of microencapsulated reactive materials. However, it turned out that the microcapsules deposited in the liquid medium, created new critical parameter due to their inhomogeneity with the other components.
Filled and/or thixotropic single-component materials, containing microencapsulated reactive materials and/or inert solvents, could not at all be manufactured until now, apart from the few, very slightly filled and possibly very slightly thixotropic liquids which are, without exception, soft fillers.
Furthermore, all the processing manipulations, associated with the manufacture of the above described materials are uneconomical.
Thus, in the entire technology, including the trade and the domestic sectors, there exists a real need for a single-component, reactive, thixotropic and/or moldable material, which does not possess the disadvantages mentioned hereinabove.